56000001661 has 2 divisors, whose sum is σ = 56000001662. Its totient is φ = 56000001660.

The previous prime is 56000001653. The next prime is 56000001697. The reversal of 56000001661 is 16610000065.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45663416100 + 10336585561 = 213690^2 + 101669^2 .

It is a cyclic number.

It is not a de Polignac number, because 56000001661 - 2³ = 56000001653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56000001641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28000000830 + 28000000831.

It is an arithmetic number, because the mean of its divisors is an integer number (28000000831).

Almost surely, 2^56000001661 is an apocalyptic number.

It is an amenable number.

56000001661 is a deficient number, since it is larger than the sum of its proper divisors (1).

56000001661 is an equidigital number, since it uses as much as digits as its factorization.

56000001661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The spelling of 56000001661 in words is "fifty-six billion, one thousand, six hundred sixty-one".